E4OD Tranny tail shaft

How hard is it to take a tail shaft out of a tranny and put a different one in? My tranny in my 90 full size with a 351(E4OD) is bad and I can get a tranny out of a 2 wheel drive but I need to change the tail shafts. Any help will be helpful!!!
Thanks,
George

If your bushing is bad they make a puller which goes into the bushing then you push an insert into the tool and pull the bushing out. OTC,MAC,Matco,Snap-ON sell them. I changed one on an older transmission and I think you removed 4 bolts and it came off. Bolted the new piece on and was done in an hour. I had a lift which makes it easier.
Remove the one on the junkyard transmission probably a damaged core with a good tail piece first and check everything out if you can't do it take the piece to a transmission shop and pay. Or you can watch the parts puller do it for you. Make sure you tell the junkyard you want a good piece from a returned core and it should be cheap.
Be very careful and clean the unit good and don't use excessive silicion seal.
Be sure to install a new seal, change transmission fluid.